Interleukin-12 (IL-12) is a potent antitumor cytokine with significant clinical toxicities. In an effort to reduce clinical toxicities and while maintaining or improving the antitumor efficacy of IL-12, we have developed a novel biomaterials-based delivery system for local administration. We have demonstrated that co-formulations of IL- 12 with a viscous biopolymer, chitosan, can: (i) retain IL-12 in the tumor microenvironment; (ii) eradicate established colorectal, bladder and pancreatic tumors; and (iii) generate durable protection from tumor recurrence. These effects could not be reproduced by either chitosan or IL-12 alone. The goal of this proposal is to elucidate the immunologic mechanisms by which chitosan potentiates the antitumor activity of IL-12. The central hypothesis is that chitosan and IL-12 act synergistically to eradicate tumors through local retention of IL-12 in the tumor microenvironment and the generation of distinct, but complementary inflammatory processes which combine to elicit tumor-specific adaptive immune responses. Four specific aims are proposed to study these mechanisms and define the potential clinical role of local chitosan/IL-12 immunotherapy. Successful completion of this project will provide rationale for clinical translation of local chitosan/IL-12 immunotherapies for the treatment of numerous cancers. Dr. Zaharoff has received extensive training in drug delivery applications at Duke University and tumor immunology at the National Cancer Institute. The present application exploits his unique multidisciplinary skill set to study the role of chitosan in enhancing the immunomodulatory functions of IL-12. Recently, Dr. Zaharoff joined the faculty in the Biomedical Engineering Program at the University of Arkansas. Biomedical Engineering is a rapidly expanding program that is committed to achieving national recognition. The biomedical research community at the University of Arkansas is a vibrant, highly collaborative group which provides ample opportunity for intellectual stimulation, collaborative interaction and equipment sharing. The K22 award will enable the candidate to establish an academic laboratory that will focus on the development of novel delivery systems for vaccines and cancer immunotherapies. Elements of the career development plan included in this proposal include didactic training in intellectual property protection, formation of an advisory board of well funded investigators and enhancing professional networks through conference and review panel participation. PUBLIC HEALTH RELEVANCE: IL-12 is a potent cytokine that has demonstrated both significant antitumor potential in preclinical studies and severe toxicities in clinical trials. Co-formulations of IL-12 with the biopolymer chitosan can enhance the antitumor activity of IL-12 while reducing systemic toxicity. This project will study the mechanisms by which chitosan enhances the antitumor activity of IL-12 and support the potential clinical translation of chitosan/IL- 12 immunotherapy.